Form of Newton's Rings. 



225 



Whence 



- = - fl- — (16 cosylr + mcb sin f) +2k 2 cj>' 2 



P U L U 1-n 2 2F 1 



+ ifc(*-l)-^^ 8 +^(^cos^+w^sin^) a J; 



N? n' L 



^ (ty cos ^ + m<£ sin f) + ~ F</> 2 



> (i"0 





+ "^*- 1 ^ + jB»(pS»- 1 )»«*++"* ,ta + ), ]'-J 



Also, from the coordinates of C^-i, 



2 ' 



ftj. 74A: /t Zf 



Whence, by means of (i.), (ii.), and (iii.)> 



Lrin + =l_M'({:-* 1 )-^»(l«+«.)(5-« + (i-i5 : ^ : 



>■ (*•) 





We have also 



+ <£i 2 (-- -")+... to it terms] 

 + <^(-^-p)+...to£term S ]. 



►(TO 



Drawing the plane BH, perpendicular to BA and B'A' as 

 before, the retardation at F of the vibration in FE relative 

 to that in FE' is 



And 



fi . B'H = ^ 1 (f' — «) + fimi(r)' — v) 



= l(?-u) + m{r)'-v) 

 Also 



